1. Field of the Invention
The present invention relates to the field of pre-stressed reinforced concrete tanks for the containment of liquids. The invention relates particularly to a mechanical device for winding the reinforcing wire or cable. It relates further to electronics for controlling the winding. It relates further to reinforcing said tanks against seismic forces.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Concrete tanks are often constructed using machines to pre-stress a cylindrical structure by continually wrapping a wire cable or tape around the structure. They are also used to spray a protective shotcrete cover coat over and under the prestressing materials. The pitch for either process is controlled by raising or lowering an elevator that is housed in a tower that continually rotates around the structure. This raising and lowering can take place once per revolution of the tower or in fractions of a revolution.
Examples of such machines are in U.S. Pat. No. 3,666,189 issued May 30, 1972 and U.S. Pat. No. 4,884,747 issued Dec. 5, 1989, both to Dykmans. Other patents are U.S. Pat. No. 2,797,878; to Crom; and U.S. Pat. No. 4,801,103 to Preload.